Method and apparatus for transmitting control information in wireless communication system

ABSTRACT

The present invention relates to a wireless communication system. In particular, the present invention relates to a method and apparatus for transmitting control information by means of a terminal in a CA-based wireless communication system, including the steps of: forming first and second cells that include different subframe configurations, wherein the second cell includes TDD UL-DL configuration #0; receiving a UL grant by means of the first cell; and transmitting data corresponding to the UL grant by means of the second cell.

TECHNICAL FIELD

The present invention relates to a wireless communication system and,more particularly, to a method for transmitting control information in acarrier aggregation (CA) based wireless communication system and anapparatus for the same.

BACKGROUND ART

Wireless communication systems have been widely deployed to providevarious types of communication services including voice and dataservices. In general, a wireless communication system is a multipleaccess system that supports communication among multiple users bysharing available system resources (e.g. bandwidth, transmit power,etc.) among the multiple users. The multiple access system may adopt amultiple access scheme such as code division multiple access (CDMA),frequency division multiple access (FDMA), time division multiple access(TDMA), orthogonal frequency division multiple access (OFDMA), or singlecarrier frequency division multiple access (SC-FDMA).

DISCLOSURE Technical Problem

An object of the present invention devised to solve the problem lies ina method for transmitting control information in a CA-based wirelesscommunication system and an apparatus for the same. Another object ofthe present invention is to provide a method for efficientlytransmitting/receiving acknowledgement information on an uplink signaland an apparatus for the same.

The technical problems solved by the present invention are not limitedto the above technical problems and those skilled in the art mayunderstand other technical problems from the following description.

Technical Solution

The object of the present invention can be achieved by providing amethod for performing a hybrid automatic repeat request (HARQ) procedureby a user equipment (UE) in a carrier aggregation (CA)-based wirelesscommunication system, the method including: configuring a first cell anda second cell having different subframe configurations, the second cellhaving time division duplex uplink-downlink (TDD UL-DL) configuration#0; receiving a UL grant through the first cell; and transmitting datacorresponding to the UL grant through the second cell, wherein aphysical hybrid ARQ indicator channel (PHICH) resource for the data isdetermined by the following equations in the first cell,

n _(PHICH) ^(group)=(I _(PRB) _(—) _(RA) +n _(DMRS))mod N _(PHICH)^(group) +I _(PHICH) N _(PHICH) ^(group)

n _(PHICH) ^(seq)=(└I _(PRB) _(—) _(RA) /N _(PHICH) ^(group) ┘+n_(DMRS))mod 2N _(SF) ^(PHICH)

wherein n_(PHICH) ^(group) represents a PHICH group index, n_(PHICH)^(seq) represents an orthogonal sequence index, I_(PRB) _(—) _(RA)denotes a value relates to the index of a resource block used totransmit the data n_(DMRS) is obtained from a value of a demodulationreference signal (DMRS)-related field in scheduling information,N_(PHICH) ^(group) indicates the number of PHICH groups, N_(SF) ^(PHICH)indicates an orthogonal sequence length, and I_(PHICH) is 0 or 1,wherein retransmission for the data is performed on the basis of atleast one of the PHICH and the UL grant when PHICH resource ofI_(PHICH)=0 is corresponding to the data, wherein retransmission for thedata is performed on the basis of only the UL grant when PHICH resourceof I_(PHICH)=1 is corresponding to the data.

In another aspect of the present invention, provided herein is a UEconfigured to perform a HARQ procedure in a CA-based wirelesscommunication system, the UE including: a radio frequency (RF) unit; anda processor, wherein the processor is configured to configure a firstcell and a second cell having different subframe configurations, thesecond cell having time division duplex uplink-downlink (TDD UL-DL)configuration #0, to receive a UL grant through the first cell and totransmit data corresponding to the UL grant through the second cell,wherein a physical hybrid ARQ indicator channel (PHICH) resource for thedata is determined by the following equations in the first cell,

n _(PHICH) ^(group)=(I _(PRB) _(—) _(RA) +n _(DMRS))mod N _(PHICH)^(group) +I _(PHICH) N _(PHICH) ^(group)

n _(PHICH) ^(seq)=(└I _(PRB) _(—) _(RA) /N _(PHICH) ^(group) ┘+n_(DMRS))mod 2N _(SF) ^(PHICH)

wherein n_(PHICH) ^(group) represents a PHICH group index, n_(PHICH)^(seq) represents an orthogonal sequence index, I_(PRB) _(—) _(RA)denotes a value relates to the index of a resource block used totransmit the data n_(DMRS) is obtained from a value of a DMRS-relatedfield in scheduling information, N_(PHICH) ^(group) indicates the numberof PHICH groups, N_(SF) ^(PHICH) indicates an orthogonal sequencelength, and I_(PHICH) is 0 or 1, wherein retransmission for the data isperformed on the basis of at least one of the PHICH and the UL grantwhen PHICH resource of I_(PHICH)=0 is corresponding to the data, whereinretransmission for the data is performed on the basis of only the ULgrant when the PHICH resource of I_(PHICH)=1 is corresponding to thedata.

The subframe configuration of the first cell may be configured accordingto c one of TDD UL-DL configurations #1 to #6 or may be configuredaccording to frequency division duplex (FDD), and subframeconfigurations according to TDD UL-DL configurations #1 to #6 are shownin the following table,

UL-DL Subframe number configuration 0 1 2 3 4 5 6 7 8 9 0 D S U U U D SU U U 1 D S U U D D S U U D 2 D S U D D D S U D D 3 D S U U U D D D D D4 D S U U D D D D D D 5 D S U D D D D D D D 6 D S U U U D S U U Dwherein D indicates a DL subframe (SF), U indicates a UL SF and Sindicates a special SF.

The UL grant may include UL scheduling information for at least one of afirst UL SF and a second UL SF, the first UL SF preceding the second ULSF, wherein retransmission for data of the first UL SF is performed onthe basis of at least one of the PHICH and the UL grant andretransmission for data of the second UL SF is performed on the basis ofonly the UL grant.

When the PHICH resource of I_(PHICH)=1 is corresponding to the data,acknowledgement (ACK) information may be signaled to a HARQ process of amedium access control (MAC) layer in a corresponding transmission timeinterval (TTI).

The first cell may be a scheduling cell and the second cell may be ascheduled cell.

Advantageous Effects

According to the present invention, it is possible to efficientlytransmit control information in a CA-based wireless communicationsystem. In addition, it is possible to efficiently transmit/receiveacknowledgement information on an uplink signal.

The effects of the present invention are not limited to theabove-described effects and other effects which are not described hereinwill become apparent to those skilled in the art from the followingdescription.

DESCRIPTION OF DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the invention, illustrate embodiments of the inventionand together with the description serve to explain the principle of theinvention. In the drawings:

FIG. 1 illustrates a radio frame structure;

FIG. 2 illustrates a resource grid of a downlink slot;

FIG. 3 illustrates a downlink subframe structure;

FIG. 4 illustrates an uplink subframe structure;

FIGS. 5 and 6 illustrates UL grant (UG)/physical hybrid ARQ indicatorchannel (PHICH) physical uplink shared channel (PUSCH) timing;

FIGS. 7 and 8 illustrate UL grant/PHICH-PUSCH timing;

FIGS. 9 and 10 illustrate PUSCH-UL grant/PHICH timing;

FIG. 11 illustrates a PHICH signal processing procedure and processingblocks;

FIG. 12 illustrates an example of allocation of PHICHs in a controlregion;

FIG. 13 illustrates a CA-based wireless communication system;

FIG. 14 illustrates a scheduling method when a plurality of cells isconfigured;

FIGS. 15 and 16 illustrate the second layer structures in case of CA;

FIG. 17 illustrates half duplex (HD)-TDD CA;

FIG. 18 illustrates full duplex (FD)-TDD CA;

FIG. 19 illustrates a HARQ process according to an embodiment of thepresent invention; and

FIG. 20 illustrates a base station and a user equipment applicable to anembodiment of the present invention.

BEST MODE

Embodiments of the present invention are applicable to a variety ofwireless access technologies such as code division multiple access(CDMA), frequency division multiple access (FDMA), time divisionmultiple access (TDMA), orthogonal frequency division multiple access(OFDMA), and single carrier frequency division multiple access(SC-FDMA). CDMA can be implemented as a radio technology such asUniversal Terrestrial Radio Access (UTRA) or CDMA2000. TDMA can beimplemented as a radio technology such as Global System for Mobilecommunications (GSM)/General Packet Radio Service (GPRS)/Enhanced DataRates for GSM Evolution (EDGE). OFDMA can be implemented as a radiotechnology such as Institute of Electrical and Electronics Engineers(IEEE) 802.11 (Wireless Fidelity (Wi-Fi)), IEEE 802.16 (Worldwideinteroperability for Microwave Access (WiMAX)), IEEE 802.20, and EvolvedUTRA (E-UTRA). UTRA is a part of Universal Mobile TelecommunicationsSystem (UMTS). 3^(rd) Generation Partnership Project (3GPP) Long TermEvolution (LTE) is a part of Evolved UMTS (E-UMTS) using E-UTRA,employing OFDMA for downlink and SC-FDMA for uplink. LTE-Advanced(LTE-A) evolves from 3GPP LTE.

While the following description is given, centering on 3GPP LTE/LTE-Afor clarity, this is purely exemplary and thus should not be construedas limiting the present invention. It should be noted that specificterms disclosed in the present invention are proposed for convenience ofdescription and better understanding of the present invention, and theuse of these specific terms may be changed to other formats within thetechnical scope or spirit of the present invention.

In a wireless communication system, a user equipment (UE) receivesinformation from a base station (BS) on downlink (DL) and transmitsinformation to the BS on uplink (UL). In LTE(-A), DL transmission isperformed using OFDMA and uplink transmission is performed using singlecarrier frequency division multiple access (SC-FDMA).

The terms used in the specification are described.

-   -   HARQ-ACK (Hybrid Automatic Repeat request-Acknowledgement): this        represents an acknowledgment response to downlink transmission        (e.g. PDSCH (Physical Downlink Shared Channel) or SPS release        PDCCH (Semi-Persistent Scheduling release Physical Downlink        Control Channel), that is, an ACK/NACK (Negative ACK)/DTX        (Discontinuous Transmission) response (simply, ACK/NACK        (response), A/N (response)). The ACK/NACK/DTX response refers to        ACK, NACK, DTX or NACK/DTX. HARQ-ACK for a specific CC        (Component Carrier) (or cell) or HARQ-ACK of a specific CC        refers to an ACK/NACK response to downlink transmission related        to (e.g. scheduled for) the corresponding CC. A PDSCH can be        replaced by a transport block (TB) or a codeword.    -   PDSCH: this includes a DL grant PDCCH and a SPS PDSCH.    -   SPS PDSCH: this is a PDSCH transmitted using DL resources        semi-statically set according to SPS. The SPS PDSCH has no DL        grant PDCCH corresponding thereto. The SPS PDSCH is used        interchangeably with a PDSCH without (w/o) PDCCH in the        specification.    -   SPS release PDCCH: this refers to a PDCCH indicating SPS        release. A UE feeds back ACK/NACK information about an SPS        release PDCCH.    -   PCC (Primary Component Carrier) PDCCH: this refers to a PDCCH        that schedules a PCC. That is, the PCC PDCCH indicates a PDCCH        corresponding to a PDSCH on the PCC. The PCC PDCCH is        transmitted only on the PCC on the assumption that cross-carrier        scheduling (or cross-CC (component carrier) scheduling) is not        permitted for the PCC. The PCC is used interchangeably with a        primary cell (PCell).    -   SCC (Secondary Component Carrier) PDCCH: this refers to a PDCCH        that schedules an SCC. That is, the SCC PDCCH indicates a PDCCH        corresponding to a PDSCH on the SCC. The SCC PDCCH may be        transmitted on a CC (e.g. PCC) other than the SCC when        cross-carrier scheduling is permitted for the SCC. When        cross-carrier scheduling is not permitted for the SCC, the SCC        PDCCH is transmitted only on the SCC. The SCC is used        interchangeably with a second cell (SCell).    -   Cross-carrier scheduling: this refers to an operation of        transmitting a PDCCH that schedules an SCC through a CC (e.g.        PCC) instead of the SCC. When only two CCs, a PCC and an SCC,        are present, the PDCCH may be scheduled/transmitted only through        the PCC.    -   Non-cross-carrier scheduling (or non-cross-CC scheduling,        self-scheduling): this refers to an operation of        scheduling/transmitting a PDCCH that schedules a CC through the        CC.

FIG. 1 illustrates a radio frame structure.

FIG. 1( a) illustrates a type-1 radio frame structure for frequencydivision duplex (FDD). A radio frame includes a plurality of (e.g. 10)subframes each of which includes a plurality of (e.g. 2) slots in thetime domain. Each subframe has a duration of 1 ms and each slot has aduration of 0.5 ms. A slot includes a plurality of OFDM/SC-FDMA symbolsin the time domain and includes a plurality of resource blocks (RBs) inthe frequency domain.

FIG. 1( b) illustrates a type-2 radio frame structure for time divisionduplex (TDD). The type-2 radio frame includes 2 half frames. Each halfframe includes 5 subframes each of which includes 2 slots.

Table 1 shows UL-DL configurations of subframes in a radio frame in theTDD mode.

TABLE 1 Downlink- to-Uplink Uplink- Switch- downlink point Subframenumber Configuration periodicity 0 1 2 3 4 5 6 7 8 9 0  5 ms D S U U U DS U U U 1  5 ms D S U U D D S U U D 2  5 ms D S U D D D S U D D 3 10 msD S U U U D D D D D 4 10 ms D S U U D D D D D D 5 10 ms D S U D D D D DD D 6  5 ms D S U U U D S U U D

In Table 1, D denotes a downlink subframe, U denotes an uplink subframeand S denotes a special subframe. The special subframe includes DwPTS(Downlink Pilot TimeSlot), GP (Guard Period), and UpPTS (Uplink PilotTimeSlot). DwPTS is a period reserved for downlink transmission andUpPTS is a period reserved for uplink transmission.

FIG. 2 illustrates a resource grid of a DL slot.

Referring to FIG. 2, a DL slot includes a plurality of OFDMA (or OFDM)symbols in the time domain. One DL slot may include 7(6) OFDMA symbolsaccording to cyclic prefix (CP) length, and one resource block (RB) mayinclude 12 subcarriers in the frequency domain. Each element on theresource grid is referred to as a resource element (RE). One RB includes12×7(6) REs. The number NiB of RBs included in the downlink slot dependson a downlink transmit bandwidth. The structure of a UL slot may be sameas that of the DL slot except that OFDMS symbols by replaced by SC-FDMAsymbols.

FIG. 3 illustrates a DL subframe structure.

Referring to FIG. 3, a maximum of three (four) OFDMS symbols located ina front portion of a first slot within a subframe correspond to acontrol region to which a control channel is allocated. The remainingOFDMS symbols correspond to a data region to which a physical downlinkshared chancel (PDSCH) is allocated. Examples of DL control channelsinclude a physical control format indicator channel (PCFICH), a physicaldownlink control channel (PDCCH), a physical hybrid ARQ indicatorchannel (PHICH), etc. The PCFICH is transmitted at a first OFDM symbolof a subframe and carries information regarding the number of OFDMsymbols used for transmission of control channels within the subframe.The PHICH is a response of uplink transmission and carries an HARQ-ACKsignal.

A PDCCH may carry a transport format and a resource allocation of adownlink shared channel (DL-SCH), resource allocation information of anuplink shared channel (UL-SCH), paging information on a paging channel(PCH), system information on the DL-SCH, information on resourceallocation of an upper-layer control message such as a random accessresponse transmitted on the PDSCH, a set of Tx power control commands onindividual UEs within an arbitrary UE group, a Tx power control command,information on activation of a voice over IP (VoIP), etc. Downlinkcontrol information (DCI) is transmitted through the PDCCH. DCI formats0/4 (referred to as UL DCI formats hereinafter) for UL scheduling (or ULgrant (UG)) and DCI formats 1/1A/1B/1C/1D/2/2A/2B/2C/2D (referred to asDL DCI formats) DL scheduling are defined. The DCI formats selectivelyinclude information such as hopping flag, RB allocation, MCS (ModulationCoding Scheme), RV (Redundancy Version), NDI (New Data Indicator), TPC(Transmit Power Control), DMRS (Demodulation Reference Signal) cyclicshift, etc. as necessary.

A plurality of PDCCHs can be transmitted within a control region. A UEmonitors the plurality of PDCCHs per subframe in order to check a PDCCHdestined therefor. The PDCCH is transmitted through one or more controlchannel elements (CCEs). A PDCCH coding rate may be controlled by thenumber of CCEs (i.e. CCE aggregation level) used for PDCCH transmission.A CCE includes a plurality of resource element groups (REGs). A formatof the PDCCH and the number of PDCCH bits are determined by the numberof CCEs. A BS determines a PDCCH format according to DCI to betransmitted to the UE, and attaches a cyclic redundancy check (CRC) tocontrol information. The CRC is masked with an identifier (e.g. a radionetwork temporary identifier (RNTI)) according to an owner or usage ofthe PDCCH. If the PDCCH is for a specific UE, then an identifier (e.g.,cell-RNTI (C-RNTI)) of the UE may be masked to the CRC. If the PDCCH isfor a paging message, then a paging identifier (e.g., paging-RNTI(P-RNTI)) may be masked to the CRC. If the PDCCH is for systeminformation (more specifically, a system information block (SIB)), thena system information RNTI (SI-RNTI) may be masked to the CRC. When thePDCCH is for a random access response, then a random access-RNTI(RA-RNTI) may be masked to the CRC.

FIG. 4 illustrates a UL subframe structure.

Referring to FIG. 4, a UL subframe includes a plurality of (e.g. 2)slots. A slot may include different numbers of SC-FDMA symbols accordingto CP lengths. The UL subframe is divided into a control region and adata region in the frequency domain. The data region is used to carry adata signal such as audio data through a physical uplink shared channel(PUSCH). The control region is used to carry uplink control information(UCI) through a physical uplink control channel (PUCCH). The PUCCHincludes an RB pair located at both ends of the data region in thefrequency domain and hopped in a slot boundary.

The PUCCH can be used to transmit the following control information.

-   -   SR (scheduling request): This is information used to request a        UL-SCH resource and is transmitted using On-Off Keying (OOK)        scheme.    -   HARQ-ACK: This is an acknowledgement signal for a DL signal        (e.g. a PDSCH or SPS release PDCCH). For example, a 1-bit        ACK/NACK signal is transmitted as a response to a single DL        codeword and a 2-bit ACK/NACK signal is transmitted as a        response to two DL codewords.    -   CSI (channel state information): This is feedback information        about a DL channel. The CSI includes a CQI (channel quality        indicator), RI (rank indicator), PMI (precoding matrix        indicator), PTI (precoding type indicator), etc.

Table 2 shows the mapping relationship between PUCCH formats and UCI inLTE(-A).

TABLE 2 PUCCH format UCI (Uplink Control Information) Format 1 SR(Scheduling Request) (non-modulated waveform) Format 1a 1-bit HARQACK/NACK (SR exist/non-exist) Format 1b 2-bit HARQ ACK/NACK (SRexist/non-exist) Format 2 CSI (20 coded bits) Format 2 CSI and 1- or2-bit HARQ ACK/NACK (20 bits) (corresponding to only extended CP) Format2a CSI and 1-bit HARQ ACK/NACK (20 + 1 coded bits) Format 2b CSI and2-bit HARQ ACK/NACK (20 + 2 coded bits) Format 3 HARQ ACK/NACK + SR (48coded bits) (LTE-A)

A description will be given of ACK/NACK, UG, PHICH and PUSCHtransmission timing in a CC (or cell) configured in TDD with referenceto FIGS. 5 and 6.

FIGS. 5 and 6 illustrates ACK/NACK (A/N) timing (or HARQ timing).

Referring to FIG. 5, a UE may receive one or more PDSCH signals in M DLsubframes (SFs) (S502_0 to S502_M−1) (M≧1). Each PDSCH signal includesone or more (e.g. 2) transport blocks (TBs) according to transmissionmode. A PDCCH signal indicating SPS release may be received in stepS502_0 to S502_M−1. When a PDSCH signal and/or an SPS release PDCCHsignal are present in the M DL subframes, the UE transmits ACK/NACKthrough a UL subframe corresponding to the M DL subframes via processesfor transmitting ACK/NACK (e.g. ACK/NACK (payload) generation, ACK/NACKresource allocation, etc.) (S504). ACK/NACK includes acknowledgementinformation about the PDSCH signal and/or an SPS release PDCCH receivedin step S502_0 to S502_M−1.

While ACK/NACK is transmitted through a PUCCH basically, ACK/NACK may betransmitted through a PUSCH when a PUSCH is transmitted at ACK/NACKtransmission time. When a plurality of CCs is configured for the UE, thePUCCH is transmitted only on a PCC and the PUSCH is transmitted on ascheduled CC. Various PUCCH formats shown in Table 2 may be used forACK/NACK transmission. To reduce the number of ACK/NACK bits transmittedthrough a PUCCH format, various methods such as ACK/NACK bundling andACK/NACK channel selection may be used.

As described above, in TDD, ACK/NACK relating to data received in the MDL subframes is transmitted through one UL subframe (i.e. M DL SF(s): 1UL SF) and the relationship therebetween is determined by a DASI(downlink association set index).

Table 3 shows DASI (K: {k0, k1, . . . , k_(M-1)}) defined in LTE(-A).Table 3 shows spacing between a UL subframe transmitting ACK/NACK and aDL subframe relating to the UL subframe. Specifically, when a PDSCHsignal and/or a PDCCH indicating SPS release are present in a subframen−k (kεK), the UE transmits ACK/NACK in a subframe n.

TABLE 3 TDD UL-DL Config- Subframe n uration 0 1 2 3 4 5 6 7 8 9 0 — — 6— 4 — — 6 — 4 1 — — 7, 6 4 — — — 7, 6 4 — 2 — — 8, 7, 4, 6 — — — — 8, 7,4, 6 — — 3 — — 7, 6, 11 6, 5 5, 4 — — — — — 4 — — 12, 8, 7, 11 6, 5, 4,7 — — — — — — 5 — — 13, 12, 9, 8, — — — — — — — 7, 5, 4, 11, 6 6 — — 7 75 — — 7 7 —

FIG. 6 illustrates A/N timing applied to a CC having UL-DL configuration#1. SF#0 to #9 and SF#10 to #19 respectively correspond to radio frames,and numerals in blocks denote UL subframes relating to DL subframes. Forexample, A/N corresponding to a PDSCH of SF#5 is transmitted in SF#5+7(=SF #12) and A/N corresponding to a PDSCH of SF#6 is transmitted inSF#6+6 (=SF #12). That is, both A/Ns respectively corresponding thePDSCHs of SF#5 and SF#6 are transmitted in SF #12. Similarly, A/Ncorresponding to a PDSCH of SF#14 is transmitted in SF#14+4 (=SF #18).

FIGS. 7 and 8 illustrate UG/PHICH-PUSCH timing. A PUSCH may betransmitted corresponding to a PDCCH (UG) and/or a PHICH (NACK).

Referring to FIG. 7, the UE may receive a PDCCH (UG) and/or a PHICH(NACK) (S702). Here, NACK corresponds to an A/N response to previousPUSCH transmission. In this case, the UE may initiallytransmit/retransmit one or more TBs through a PUSCH after k subframesvia processes for PUSCH transmission (e.g. TB coding, TB-CW (transportblock-codeword) swiping, PUSCH resource allocation, etc.) (S704). Thepresent embodiment is based on the assumption that a normal HARQoperation in which a PUSCH is transmitted once is performed. In thiscase, a PHICH and a UG corresponding to PUSCH transmission are presentin the same subframe. However, in case of subframe bundling in which aPUSCH is transmitted multiple times through a plurality of subframes, aPHICH and a UG corresponding to PUSCH transmission may be present indifferent subframes.

Table 4 shows a UAI (Unlink Association Index) (k) for PUSCHtransmission in LTE(-A). Table 4 shows spacing between a DL subframefrom which a PHICH/UG is detected and a UL subframe relating to the DLsubframe. Specifically, when a PHICH/UG is detected from a subframe n,the UE may transmit a PUSCH in a subframe n+k.

TABLE 4 TDD UL-DL subframe number n Configuration 0 1 2 3 4 5 6 7 8 9 04 6 4 6 1 6 4 6 4 2 4 4 3 4 4 4 4 4 4 5 4 6 7 7 7 7 5

FIG. 8 illustrates PUSCH transmission timing when UL-DL configuration #1is set. In the figure, SF#0 to #9 and SF#10 to #19 respectivelycorrespond to radio frames, and numerals in blocks denote UL subframesrelating to DL subframes. For example, a PUSCH corresponding to PHICH/UGof SF#6 is transmitted in SF#6+6 (=SF#12) and a PUSCH corresponding to aPHICH/UG of SF#14 is transmitted in SF#14+4 (=SF#18).

FIGS. 9 and 10 illustrate PUSCH-UG/PHICH timing. A PHICH is used totransmit DL ACK/NACK. Here, DL ACK/NACK refers to ACK/NACK transmittedon downlink as a response to UL data (e.g. PUSCH).

Referring to FIG. 9, the UE transmits a PUSCH signal to the BS (S902).Here, the PUSCH signal is used to transmit one or a plurality of (e.g.2) TBs according to transmission mode. The BS may transmit ACK/NACK as aresponse to PUSCH transmission through a PHICH after k subframes viaprocesses for ACK/NACK transmission (e.g. ACK/NACK generation, ACK/NACKresource allocation, etc.) (S904). A/N includes acknowledgementinformation about the PUSCH signal of step S902. When a response toPUSCH transmission is NACK, the BS may transmit a UG PDCCH for PUSCHretransmission to the UE after k subframes (S904). In a normal HARQoperation, a UG and a PHICH used for PUSCH transmission may betransmitted in the same subframe. In case of subframe bundling, however,the UG and PHICH used for PUSCH transmission may be transmitted indifferent subframes.

Table 5 shows PHICH timing defined in TDD. The UE determines a PHICHresource corresponding to a subframe #(n+k_(PHICH)) for PUSCHtransmission in a subframe #n.

TABLE 5 TDD UL-DL UL subframe index n Configuration 0 1 2 3 4 5 6 7 8 90 4 7 6 4 7 6 1 4 6 4 6 2 6 6 3 6 6 6 4 6 6 5 6 6 4 6 6 4 7

FIG. 10 illustrates UG/PHICH transmission timing when UL-DLconfiguration #1 is set. In the figure, SF#0 to #9 and SF#10 to #19respectively correspond to radio frames, and numerals in blocks denoteDL subframes relating to UL subframes. For example, a PHICH/UGcorresponding to a PUSCH of SF#2 is transmitted in SF#2+4 (=SF#6) and aPHICH/UG corresponding to a PUSCH of SF#8 is transmitted in SF#8+6(=SF#14).

FIG. 11 illustrates a PHICH signal processing procedure and processingblocks.

Referring to FIG. 11, an A/N generation block 602 generates a 1-bit A/Nsignal as a response to a PUSCH in case of MU-MIMO (multi-user multipleinput multiple output) and generates two 1-bit A/N signals as a responseto a PUSCH in case of SU-MIMO (single-user MIMO). Subsequently,(channel) coding (604) (e.g. ⅓ repetition coding)), modulation (606)(e.g. BPSK (binary phase shift keying)), spreading (608), layer mapping(610) and resource mapping (612) are applied to the A/N bit for PHICHgeneration.

A plurality of PHICHs may be mapped to the same RE (e.g. REG) to form aPHICH group. The REG is composed of 4 neighboring REs from among REsleft when REs for a reference signal are excluded on an OFDM symbol.Each PHICH is identified by an orthogonal sequence (used for spreading)in the PHICH group. Accordingly, a PHICH resource is identified by anindex pair (n_(PHICH) ^(group),n_(PHICH) ^(seq)). Here, n_(PHICH)^(group) denotes a PHICH group number and n_(PHICH) ^(seq) denotes anorthogonal sequence index. n_(PHICH) ^(group) and n_(PHICH) ^(seq) areidentified using the lowest physical RB (PRB) index from among PRBindices allocated for PUSCH transmission and a cyclic shift of a DMRStransmitted through a UG.

Equation 1 represents an example of obtaining n_(PHICH) ^(group) andn_(PHICH) ^(seq).

n _(PHICH) ^(group)=(I _(PRB) _(—) _(RA) +n _(DMRS))mod N _(PHICH)^(group) +I _(PHICH) N _(PHICH) ^(group)

n _(PHICH) ^(seq)=(└I _(PRB) _(—) _(RA) /N _(PHICH) ^(group) ┘+n_(DMRS))mod 2N _(SF) ^(PHICH)//  [Equation 1]

Here, n_(DMRS) is mapped from a DMRS field value (i.e. cyclic shift) ina UG PDCCH signal which is most recently received corresponding to PUSCHtransmission. N_(SF) ^(PHICH) denotes the size of a spreading factorused for PHICH modulation. N_(SF) ^(PHICH) is 4 in group case of normalCP and 2 in case of extended CP. N_(PHICH) ^(group) represents thenumber of PHICH groups. I_(PRB) _(—) _(RA) corresponds to I_(PRB) _(—)_(RA) ^(lowest) ^(—) ^(index) for the first TB of a PUSCH andcorresponds to I_(PRB) _(—) _(RA) ^(lowest) ^(—) ^(index) for the secondTB of the PUSCH. I_(PRB) _(—) _(RA) ^(lowest) ^(—) ^(index) denotes thelowest PRB index (of the first slot) in PUSCH transmission. I_(PHICH) is1 for PUSCH transmission in a subframe n=4 or 9 in case of TDD UL-DLconfiguration #0 and 0 in other cases.

In case of FDD (frame structure type 1), the number of PHICH groups,N_(PHICH) ^(group), is identical in all subframes and given by Equation2 in each subframe.

$\begin{matrix}{N_{PHICH}^{group} = \left\{ \begin{matrix}\left\lceil {N_{g}\left( {N_{RB}^{DL}/8} \right)} \right\rceil & {{for}\mspace{14mu} {normal}\mspace{14mu} {cyclic}\mspace{14mu} {prefix}} \\{2 \cdot \left\lceil {N_{g}\left( {N_{RB}^{DL}/8} \right)} \right\rceil} & {{for}\mspace{14mu} {extended}\mspace{14mu} {cyclic}\mspace{14mu} {prefix}}\end{matrix} \right.} & \left\lbrack {{Equation}\mspace{14mu} 2} \right\rbrack\end{matrix}$

Here, N_(g)ε{⅙, ½, 1, 2} is provided by a higher layer and N^(DL) _(RB)denotes the number of RBs of a DL band.

In case of TDD (Frame structure type 2), the number of PHICH groupsdepends on DL subframe and is given by m_(i)·N_(PHICH) ^(group). Table 6shows m_(i). A PHICH resource (or the quantity of PHICH resources) whenm_(i)=1 is referred to as 1×PHICH resource and a PHICH resource (or thequantity of PHICH resources) when m_(i)=2 is referred to as 2×PHICHresource for convenience.

TABLE 6 Uplink-downlink Subframe number i configuration 0 1 2 3 4 5 6 78 9 0 2 1 — — — 2 1 — — — 1 0 1 — — 1 0 1 — — 1 2 0 0 — 1 0 0 0 — 1 0 31 0 — — — 0 0 0 1 1 4 0 0 — — 0 0 0 0 1 1 5 0 0 — 0 0 0 0 0 1 0 6 1 1 —— — 1 1 — — 1

Table 7 shows orthogonal sequences used to spread A/N bits.

TABLE 7 Orthogonal sequence Sequence Normal cyclic Extended cyclic indexprefix prefix n_(PHICH) ^(seq) N_(SF) ^(PHICH) = 4 N_(SF) ^(PHICH) = 2 0[+1 +1 +1 +1] [+1 +1] 1 [+1 −1 +1 −1] [+1 −1] 2 [+1 +1 −1 −1] [+j +j] 3[+1 −1 −1 +1] [+j −j] 4 [+j +j +j +j] — 5 [+j −j +j −j] — 6 [+j +j −j−j] — 7 [+j −j −j +j] —

FIG. 12 illustrates an example of allocation of PHICHs in a controlregion. PHICHs are mapped to REGs other than REGs corresponding to aPCFICH and RS (reference signal) in OFDMA symbols.

Referring to FIG. 12, a PHICH group is transmitted using 3 REGs spacedas far apart as possible in the frequency domain. Consequently, each bitof an A/N codeword is transmitted through each REG. PHICH groups areconsecutively allocated in the frequency domain. In the figure, the samenumeral denotes REGs belonging to the same PHICH group. A PHICH durationis limited by the size of the control region and the number of OFDMsymbols (PHICH duration) used for PHICH transmission corresponds to oneto three OFDMA symbols. When a plurality of OFDMA symbols is used forPHICH transmission, REGs belonging to the same PHICH group aretransmitted using different OFDMA symbols.

A plurality of parallel HARQ processes for UL transmission is presentfor a UE. The parallel HARQ processes continuously perform ULtransmission while the UE waits for HARQ feedback for successful ornon-successful reception with respect to previous UL transmission. EachHARQ process is related to a HARQ buffer of a medium access control(MAC) layer. Each HARQ process manages state variables with respect tothe number of transmissions of a MAC PDU (physical data block) in thebuffer, HARQ feedback for the MAC PDU in the buffer, redundancy version(RV), etc. In addition, the HARQ process is related to a soft buffer forTBs and a soft buffer for code blocks in a physical layer PHY.

In case of LTE(-A) FDD, the number of UL HARQ processes for non-subframebundling operation (i.e. normal HARQ operation) is 8. Since the numberof UL subframes depends on UL-DL configuration in case of LTE(-A) TDD,the number of UL HARQ processes and HARQ RTT (round trip time) depend onUL-DL configuration. Here, the HARQ RTT may refer to an interval (e.g.in the unit of SF or ms) from when a UL grant is received, then viatransmission of a PUSCH (corresponding to the UL grant), to when a PHICH(corresponding to the UL grant) is received or interval from PUSCHtransmission timing to retransmission timing. When subframe bundling isapplied, a PUSCH group composed of four consecutive UL subframes istransmitted in FDD and TDD. Accordingly, a HARQ operation/process whensubframe bundling is applied differs from the normal HARQoperation/process.

Table 8 shows the maximum number of DL HARQ processes according to UL-DLconfiguration in TDD.

TABLE 8 TDD UL-DL Maximum number of configuration HARQ processes 0 4 1 72 10 3 9 4 12 5 15 6 6

Table 9 shows the number of synchronous UL HARQ processes and HARQ RTTin TDD. The number of UL SFs is defined per UL-DL Cfg, and the number ofUL HARQ processes and the (UL) HARQ RTT are set according to UL-DLconfiguration on the basis of the number of UL SFs per UL-DL Cfg. TheHARQ RTT may refer to an interval (e.g. in the unit of SF or ms) fromwhen a UL grant is received, then via transmission of a PUSCH(corresponding to the UL grant), to when a PHICH (corresponding to theUL grant) is received or interval from PUSCH transmission timing toretransmission timing. When the UL HARQ RTT is 10 [SFs or ms] (UL-DLconfigurations #1, #2, #3, #4 and #5), one UL HARQ process uses onefixed UL SF timing. When the UL HARQ RTT is not 10 [SFs or ms] (UL-DLconfigurations #0 and #6), one UL HARQ process uses a plurality of UL SFtimings (while hopping the same). For example, in case of UL-DLconfiguration #6, PUSCH transmission timing in a UL HARQ process may be:SF #2: PUSCH=>SF #13: PUSCH (RTT: 11 SFs)=>SF #24: PUSCH (RTT:11SFs)=>SF #37: PUSCH (RTT: 13 SFs)=>SF #48: PUSCH (RTT: 11SFs)=>SF #52:PUSCH (RTT: 14 SFs).

TABLE 9 UL-DL Number of Number of HARQ processes configuration UL SFsfor normal HARQ operation HARQ RTT 0 6 7 11 or 13 1 4 4 10 2 2 2 10 3 33 10 4 2 2 10 5 1 1 10 6 5 6 11 or 13 or 14

When a UL grant PDCCH and/or a PHICH are detected from a subframe n incase of TDD UL-DL configurations #1 to #6 and normal HARQ operation, theUE transmits a corresponding PUSCH signal in a subframe n+k (refer toTable 4) according to PDCCH and/or PHICH information.

When a UL DCI grant PDCCH and/or a PHICH are detected from a subframe nin case of TDD UL-DL configuration #0 and normal HARQ operation, PUSCHtransmission timing of the UE depends on the situation. When the MSB(most significant bit) of a UL index in DCI is 1 or the PHICH isreceived through a resource corresponding to I_(PHICH)=0 in subframe #0or #5, the UE transmits the corresponding PUSCH signal in the subframen+k (refer to Table 4). When the LSB (least significant bit) of the ULindex in the DCI is 1, the PHICH is received through a resourcecorresponding to I_(PHICH)=1 in subframe #0 or #5, or the PHICH isreceived through subframe #1 or #6, the UE transmits the correspondingPUSCH signal in a subframe n+7. When the MSB and LSB in the DCI are bothset, the UE transmits the corresponding PUSCH signal in the subframe n+4(refer to Table 4) and the subframe n+7.

A description will be given of operations of a HARQ entity and HARQprocess in more detail with reference to 3GPP TS 36.321 V10.5.0(2012-03) opened before initial provisional application of the presentinvention.

Tables 10 and 11 show operations of the HARQ entity and HARQ process.

TABLE 10 For each TTI, the HARQ entity shall: identify the HARQprocess(es) associated with this TTI, and for each identified HARQprocess if an uplink grant has been indicated for this process and thisTTI: if the received grant was not addressed to a Temporary C-RNTI onPDCCH and if the NDI provided in the associated HARQ information hasbeen toggled compared to the value in the previous transmission of thisHARQ process; or if the uplink grant was received on PDCCH for theC-RNTI and the HARQ buffer of the identified process is empty; or if theuplink grant was received in a Random Access Response: if there is a MACPDU in the Msg3 buffer and the uplink grant was received in a RandomAccess Response: obtain the MAC PDU to transmit from the Msg3 buffer.else: obtain the MAC PDU to transmit from the “Multiplexing andassembly” entity; deliver the MAC PDU and the uplink grant and the HARQinformation to the identified HARQ process; instruct the identified HARQprocess to trigger a new transmission. else: deliver the uplink grantand the HARQ information (redundancy version) to the identified HARQprocess; instruct the identified HARQ process to generate an adaptiveretransmission. else, if the HARQ buffer of this HARQ process is notempty: instruct the identified HARQ process to generate a non-adaptiveretransmission.

TABLE 11 When the HARQ feedback is received for this TB, the HARQprocess shall: set HARQ_FEEDBACK to the received value. If the HARQentity requests a new transmission, the HARQ process shall: setCURRENT_TX_NB to 0; set CURRENT_IRV to 0; store the MAC PDU in theassociated HARQ buffer; store the uplink grant received from the HARQentity; set HARQ_FEEDBACK to NACK; generate a transmission as describedbelow. If the HARQ entity requests a retransmission, the HARQ processshall: increment CURRENT_TX_NB by 1; if the HARQ entity requests anadaptive retransmission: store the uplink grant received from the HARQentity; set CURRENT_IRV to the index corresponding to the redundancyversion value provided in the HARQ information; set HARQ_FEEDBACK toNACK; generate a transmission as described below. else if the HARQentity requests a non-adaptive retransmission: if HARQ_FEEDBACK = NACK:generate a transmission as described below. NOTE: When receiving a HARQACK alone, the UE keeps the data in the HARQ buffer. NOTE: When noUL-SCH transmission can be made due to the occurrence of a measurementgap, no HARQ feedback can be received and a non-adaptive retransmissionfollows.

FIG. 13 illustrates a carrier aggregation (CA)-based wirelesscommunication system. To use a wider frequency band, an LTE-A systememploys CA which aggregates a plurality of UL/DL frequency blocks toobtain a wider UL/DL bandwidth although an LTE system supports only asingle DL/UL frequency block. Each frequency block is transmitted usinga component carrier (CC). The CC may be regarded as a carrier frequency(or center carrier, center frequency) for the frequency block.

Referring to FIG. 13, according to CA, a plurality of UL/DL CCs can beaggregated to support a wider UL/DL bandwidth. The CCs may be contiguousor non-contiguous in the frequency domain. Bandwidths of the CCs can beindependently determined Asymmetrical CA in which the number of UL CCsis different from the number of DL CCs can be implemented. For example,when there are two DL CCs and one UL CC, the DL CCs can correspond tothe UL CC in the ratio of 2:1. A DL CC/UL CC link may be fixed orsemi-statically configured in the system. Even if the system bandwidthis configured with N CCs, a frequency band that a specific UE can usemay be limited to L (<N) CCs. Various parameters with respect to CA maybe set cell-specifically, UE-group-specifically, or UE-specifically.Control information may be transmitted/received only through a specificCC. This specific CC may be referred to as a primary CC (PCC) (or anchorCC) and other CCs can be referred to as secondary CCs (SCCs).

In LTE-A, the concept of a cell is used to manage radio resources. Acell is defined as a combination of DL resources and UL resources. Yet,the UL resources are not mandatory. Therefore, a cell may be composed ofDL resources only or both DL resources and UL resources. The linkagebetween the carrier frequencies (or DL CCs) of DL resources and thecarrier frequencies (or UL CCs) of UL resources may be indicated bysystem information when CA is supported. A cell operating in primaryfrequency resources (or a PCC) may be referred to as a primary cell(PCell) and a cell operating in secondary frequency resources (or anSCC) may be referred to as a secondary cell (SCell). The PCell is usedfor a UE to establish an initial connection or re-establish aconnection. The PCell may refer to a cell indicated during handover. TheSCell may be configured after an RRC connection is established and maybe used to provide additional radio resources. The PCell and the SCellmay collectively be referred to as a serving cell. Accordingly, a singleserving cell composed of a PCell only exists for a UE in anRRC_Connected state, for which CA is not set or which does not supportCA. On the other hand, one or more serving cells exist, including aPCell and one or more SCells, for a UE in an RRC_CONNECTED state, forwhich CA is set.

The above description (FIGS. 1 to 13) is applicable to each CC (or cell)when a plurality of CCs (or cells) is aggregated unless otherwisementioned. In addition, a CC may be used interchangeably with a servingCC, a serving carrier, a cell, a serving cell, etc.

When a plurality of CCs is configured, cross-CC scheduling andnon-cross-CC scheduling may be used. Non-cross-CC scheduling correspondsto scheduling in LTE. When cross-CC scheduling is applied, a DL grantPDCCH may be transmitted on DL CC#0 and a PDSCH corresponding theretomay be transmitted on DL CC#2. Similarly, a UL grant PDCCH may betransmitted on DL CC#0 and a PUSCH corresponding thereto may betransmitted on DL CC#4. For cross-CC scheduling, a carrier indicatorfield (CIF) is used. Presence or absence of a CIF in a PDCCH may besemi-statically and UE-specifically (or UE-group-specifically)configured through higher layer signaling (e.g. RRC signaling).

Scheduling according to the CIF may be arranged as follows.

-   -   CIF disabled: a PDCCH on a DL CC is used to allocate a PDSCH        resource on the same DL CC or a PUSCH resource on a linked UL        CC.    -   CIF enabled: a PDCCH on a DL CC can be used to allocate a PDSCH        or PUSCH resource on a specific DL/UL CC from among a plurality        of aggregated DL/UL CCs using the CIF.

When the CIF is present, the BS may allocate a monitoring DL CC toreduce blind detection complexity of the UE. For PDSCH/PUSCH scheduling,the UE may detect/decode a PDCCH only on the corresponding DL CCs. Inaddition, the BS may transmit a PDCCH only through the monitoring DL CC(set). The monitoring DL CC set may be UE-specifically,UE-group-specifically or cell-specifically configured.

FIG. 14 illustrates cross-carrier scheduling. While the figure shows DLscheduling, cross-carrier scheduling is equally applied to ULscheduling.

Referring to FIG. 14, 3 DL CCs are configured for a UE, and DL CC A maybe set as a PDCCH monitoring DL CC. When the CIF is disabled, each DL CCcan transmit only a PDCCH that schedules a PDSCH corresponding to the DLCC without a CIF according to LTE PDCCH rule. When the CIF is enabled,DL CC A (i.e. MCC) can transmit not only a PDCCH that schedules thePDSCH corresponding to the DL CC A but also PDCCHs that schedule PDSCHsof other DL CCs using the CIF. In this case, a PDCCH is not transmittedin DL CC B/C.

Here, a specific CC (or cell) used to transmit scheduling information(e.g. PDCCH) is referred to as “monitoring CC (MCC)” which may bereplaced by “monitoring carrier”, “monitoring cell”, “schedulingcarrier”, “scheduling cell”, “scheduling CC”, etc. A DL CC on which aPDSCH corresponding to a PDCCH is transmitted and a UL CC on which aPUSCH corresponding to a PUCCH is transmitted may be referred to as ascheduled carrier, a scheduled CC, a scheduled cell, etc. One or morescheduling CCs may be configured per UE. A scheduling CC may include aPCC. When only one scheduling CC is configured, the scheduling CC may bethe PCC. The scheduling CC may be UE-specifically, UE-group-specificallyor cell-specifically set.

In case of cross-CC scheduling, signal transmission may be performed asfollows.

-   -   PDCCH (UL/DL grant): scheduling CC (or MCC)    -   PDSCH/PUSCH: CC indicated by a CIF of a PDCCH detected from a        scheduling CC    -   DL ACK/NACK (e.g. PHICH): scheduling CC (or MCC) (e.g. DL PCC)    -   UL ACK/NACK (e.g. PUCCH): UL PCC

* In the following description, DL ACK/NACK may be referred to as DL A/Nor PHICH and UL ACK/NACK may be referred to as UL A/N or A/N forconvenience.

FIGS. 15 and 16 illustrate second layer (Layer 2) structures. A firstlayer (i.e. physical layer (PHY)) is present under the second layer anda third layer (e.g. RRC layer) is present above the second layer. FIG.15 shows the second layer structure of the BS and FIG. 16 shows thesecond layer structure of the UE. CA considerably affects the MAC layerof the second layer. For example, the MAC layer of a CA system performsoperation related to a plurality of HARQ entities since a plurality ofCCs is aggregated in CA and one HARQ entity (HARQ block in the figures)manages one CC. HARQ entities independently process TBs, and thus aplurality of TBs can be transmitted or received through a plurality ofCCs at the same time. Each HARQ entity manages operations of a pluralityof HARQ processes (HARQp).

Embodiment A/N Transmission when CCs Having Different SubframeConfigurations are Aggregated

A conventional CA TDD system considers only a case in which a pluralityof serving cells (e.g. PCell and SCell) having the same TDD UL-DLconfiguration is aggregated. However, a beyond LTE-A system considersaggregation of a plurality of CCs having different subframeconfigurations. For example, aggregation of a plurality of CCs havingdifferent subframe configurations includes aggregation of a plurality ofCCs having different UL-DL configurations (referred to as different TDDCA for convenience) and aggregation of TDD CC and FDD CC. While thefollowing description is based on different TDD CA, aggregation of aplurality of CCs having different subframe configurations is not limitedthereto. In the case of different TDD CA, A/N timings (refer to FIGS. 5and 6) configured for a PCC and SCC may differ from each other accordingto UL-DL configurations thereof. Accordingly, different UL SF timings atwhich A/N is transmitted may be configured for the PCC and SCC for thesame DL SF timing and different DL SF groups to which A/N feedback istransmitted at the same UL SF timing may be configured for the PCC andSCC. In addition, link directions (i.e. DL/UL) of the PCC and SCC maydiffer from each other for the same SF timing.

Furthermore, the beyond LTE-A system considers supporting of cross-CCscheduling operation even when a plurality of CCs having differentsubframe configurations is aggregated. In this case, UL grant/PHICHtimings (refer to FIGS. 7 to 10) configured for an MCC and SCC maydiffer from each other. For example, different DL SFs in which a ULgrant/PHICH is transmitted may be set for the MCC and SCC for the sameUL SF. In addition, for a UL grant or PHICH feedback transmitted in thesame DL SF, different UL SF groups may be set for the MCC and SCC. Evenin this case, link directions of the MCC and SCC may differ from eachother for the same SF timing. For example, specific SF timing may be setto a DL SF in which a UL grant/PHICH will be transmitted for the SCCwhereas such SF timing may be set to a UL SF for the MCC.

When SF timing (referred to as a collided SF hereinafter) at which linkdirections of the PCC (or MCC) and SCC are different from each other ispresent due to different subframe configurations (e.g. different TDDCA), only a CC having a specific link direction or the same linkdirection as a specific CC (e.g. PCC (or MCC)) between the PCC (or MCC)and SCC may be operated at the SF timing due to UE hardwareconfiguration or for other reasons/purposes. Such scheme is referred toas half-duplex (HD)-TDD CA for convenience. For example, when a specificSF timing with respect to the PCC (or MCC) is set to a DL SF and the SFtiming with respect to the SCC is set to a UL SF to generate a collidedSF, only the PCC (or MCC) (i.e. DL SF set to the PCC (or MCC)) having aDL direction at the corresponding SF timing may be operated and the SCC(i.e. UL SF set to the SCC)) having a UL direction at the SF timing maynot be operated (and vice versa).

In this case, to transmit a UG/PHICH for UL data transmitted through anMCC UL SF and an SCC UL SF cross-CC-scheduled through the MCC, the sameor different UG/PHICH timing (set to a specific UL-DL configuration) maybe applied per CC or UG/PHICH timing configured as the specific UL-DLconfiguration may be commonly applied to all CCs (i.e. PCC (or MCC) andSCC). The specific UL-DL configuration (referred to as a referenceconfiguration (Ref-Cfg), hereinafter) may correspond to a UL-DLconfiguration (MCC-Cfg) set to the PCC (or MCC) or a UL-DL configuration(SCC-Cfg) set to the SCC or may be determined as a UL-DL configurationother than MCC-Cfg and SCC-Cfg. FIG. 17 illustrates HD-TDD CA. In thefigure, a shaded portion X represents a CC (link direction) which isrestricted to be used in the collided SF.

A method of permitting simultaneous UL/DL transmission/reception in thecollided SF in which link directions of the PCC (or MCC) and SCC differfrom each other may be considered. Such method is referred to as fullduplex (FD)-TDD CA for convenience. In this case, to transmit a UG/PHICHfor a UL SF of the PCC (or MCC) and a UL SF of the SCC, which iscross-CC-scheduled through the PCC (or MCC), through the PCC (or MCC),the same or different UG/PHICH timing (set to a specific UL-DLconfiguration (i.e. Ref-Cfg)) may be applied or UG/PHICH timingconfigured as the specific UL-DL configuration (i.e. Ref-Cfg) may becommonly applied to all CCs (i.e. PCC (or MCC) and SCC). Ref-Cfg maycorrespond to MCC-Cfg or SCC-Cfg or may be determined as UL-DL Cfg otherthan MCC-Cfg and SCC-Cfg. FIG. 18 illustrates FD-TDD CA.

In the specification, D denotes a DL SF or a specific SF and Urepresents a UL SF. When a UL-DL configuration (UD-cfg) of a CC is(semi-)statically set through broadcast information or higher layersignaling, a subframe configuration of the CC may be determined on thebasis of Table 1. A/N timing may refer to U configured totransmit/receive A/N for DL data of a specific D or timing relationshipthereof. UG or PHICH timing may refer to D configured totransmit/receive a UG that schedules UL data of a specific U and a PHICHfor transmission of the UL data or timing relationship thereof.Specifically, application of ACK/NACK timing set to a specific CC (i.e.Ref-CC) or specific UD-Cfg (i.e. Ref-cfg) may refer to use of UD-Cfg ofthe specific CC or a parameter value corresponding to the specificUD-Cfg in Table 3. In addition, application of UL grant or PHICH timingset to the specific CC (i.e. Ref-CC) or specific UD-cfg (i.e. Ref-cfg)may refer to use of UD-Cfg of the specific CC or a parameter valuecorresponding to the specific UD-cfg in Tables 4 and 5.

In the present invention, Ref-Cfg for a UL data HARQ process (i.e. UG orPHICH timing) may be determined as follows according to whether cross-CCscheduling is applied or not.

[Solution 1]

-   -   UL grant/PHICH for UL data transmitted through the MCC        -   UL grant/PHICH timing set to the MCC is applied.    -   UL grant/PHICH for UL data transmitted through the SCC        -   Non-cross-CC scheduling: UL grant/PHICH timing set to the            SCC is applied.        -   Cross-CC scheduling: UL grant/PHICH timing (referred to as            UL union timing hereinafter) of a UL-DL configuration            (referred to as UL union hereinafter) having the smallest            number of Us from among UL-DL configurations in which SFs,            where MCC or SCC is U, are all set to U is applied.            Equivalently, UL grant/PHICH timing of a UL-DL configuration            (i.e. UL union) having the largest number of Ds from among            UL-DL configurations in which SFs, where MCC or SCC is U,            are all set to U is applied.

[Solution 2]

-   -   UL grant/PHICH for UL data transmitted through the MCC        -   UL grant/PHICH timing set to the MCC is applied.    -   UL grant/PHICH for UL data transmitted through the SCC        -   Non-cross-CC scheduling: UL grant/PHICH timing set to the            SCC is applied.        -   Cross-CC scheduling: UL grant/PHICH timing set to the MCC is            applied. Scheduling of U of the SCC may be abandoned for a            collided SF in which the MCC (and/or PCC) corresponds to D            and the SCC corresponds to U (i.e. the collided SF is            excluded from available U (in terms of UL grant/PHICH)).            Accordingly, UL grant/PHICH timing may not be defined for            the collided SF. Therefore, the collided SF may not be            considered for the number of HARQ processes, HARQ RTT            determination, etc. or may be processed as NACK (or DTX or            NACK/DTX).

UL-DL configuration #0 in which the number of UL SFs is greater than thenumber of DL SFs has characteristics different from other DL-ULconfigurations. For example, a UL DAI (downlink assignment index) isincluded in a UL grant DCI format in the case of UL-DL configurations #1to #6, whereas a UL index rather than the UL DAI is included in the ULgrant DCI format in the case of UL-DL configuration #0. Here, the ULindex indicates a UL SF to be scheduled. That is, in the case of UL-DLconfiguration #0, the UL index is used in order to perform UL datascheduling/HARQ process for a large number of UL SFs using a smallnumber of DL SFs. In the case of UL-DL configurations #1 to #6, a DL DAIin a DL grant DCI format indicates a PDCCH order value (or countervalue). In the case of UL-DL configuration #0, the DL DAI is notsignaled while the DL DAI is included in the DL grant DCI format. DL DAIsignaling may be omitted in the case of UL-DL configuration #0 since thenumber of UL SFs is greater than the number of DL SFs and thus differentUL SFs can be linked to DL SFs (for A/N transmission). Here, the DLgrant DCI format may include not only a PDCCH that schedules DL data butalso a PDCCH that orders SPS release.

Accordingly, UD-Cfg #0 permits an operation through which a single ULgrant PDCCH simultaneously schedules a plurality of (e.g. 2) pieces ofUL data, which are respectively transmitted through a plurality of (e.g.2) UL SFs, unlike other UD-Cfgs. In view of this, a larger amount (e.g.twice) of PHICH resources is reserved in a specific DL SF, compared to anormal case.

Specifically, referring back to Equation 1 and Table 6, when PHICHs withrespect to two UL SFs (UL data transmitted through the UL SFs) aresimultaneously transmitted in specific DL SFs (e.g. DL SFs #0 and #5),the PHICH resource index corresponding to the first UL SF(chronologically) may be determined as a PHICH resource index obtainedby applying I_(PHICH)=0 to Equation 1 and the PHICH resource indexcorresponding to the second UL SF may be determined as a PHICH resourceindex obtained by applying I_(PHICH)=1 to Equation 1. Equation 1 isshown below for convenience.

n _(PHICH) ^(group)=(I _(PRB) _(—) _(RA) +n _(DMRS))mod N _(PHICH)^(group) +I _(PHICH) N _(PHICH) ^(group)

n _(PHICH) ^(seq)=(└I _(PRB) _(—) _(RA) /N _(PHICH) ^(group) ┘+n_(DMRS))mod 2N _(SF) ^(PHICH)

When the SCC is set to UD-Cfg #0 and the MCC is set to UL-Cfg other thanUD-Cfg #0 in case of cross-CC scheduling, solution 1 is applicable. Whensolution 1 is applied, Ref-Cfg of UG/PHICH timing for UL data (SCC ULdata) (e.g. SCC PUSCH) transmitted through the SCC may be determined asa UL union of the MCC and SCC, UD-Cfg #0 (i.e. SCC UD-Cfg). Here, aPHICH for the SCC UL data is transmitted from the MCC since cross-CCscheduling is used and only 1×PHICH resource is reserved in a DL SFsince the MCC does not correspond to UD-Cfg #0. Accordingly, whentransmission of PHICHs for two SCC UL SFs needs to be performed in asingle MCC DL SF, the conventional PHICH resource determination andtransmission scheme cannot be used.

To solve the aforementioned problem, the present invention proposes amethod of determining a PHICH resource transmitting a PHICH signal forA/N feedback for SCC UL data when SCC UD-Cfg corresponds to UD-Cfg #0 incase of TDD CA based cross-CC scheduling between different UD-Cfgs. Tounderstand the present invention, it is assumed that Ref-Cfg of UG/PHICHtiming for UL data transmitted through an SCC corresponding to UD-Cfg #0is determined as UD-Cfg #0 (i.e. SCC UD-Cfg) according to solution 1 inthe proposed method. The method proposed by the present invention may begeneralized as a method of determining and transmitting a PHICH resourcecorresponding to SCC UL data when UD-Cfg of MCC does not correspond toUD-Cfg #0 (e.g. MCC UD-Cfg=UD-Cfgs #1 to #6; MCC=FDD CC) and Ref-Cfg ofUG/PHICH timing for the SCC is set to UD-Cfg #0. The method isapplicable even when a plurality of SCCs is present and may be used forMCC/SCC combinations.

Specifically, when a DL SF of the MCC, which corresponds to common PHICHtiming for two specific UL SFs (two pieces of UL data transmittedthrough the UL SFs) on the SCC, belongs to UG/PHICH timing (e.g. a DL SFin which a PHICH resource is reserved) set to the MCC (i.e. when PHICHresource allocation and transmission for two pieces of UL data aresimultaneously needed while only 1×PHICH resource is reserved), thefollowing PHICH resource allocation and transmission method is provided.The two pieces of UL data are respectively referred to as UL SF-1 and ULSF-2 and it is assumed that UL SF-1 precedes UL SF-2.

Alt 0) I_(PHICH)=0 is Applied to all UL SFs to Obtain PHICH ResourceIndex

When PHICH resources corresponding to UL SF-1 and UL SF-2 are determined(refer to Equation 1), I_(PHICH)=0 is applicable to both UL SF-1 and ULSF-2. Specifically, a PHICH resource index corresponding to UL SF-1 maybe assigned a PHICH resource index linked to the lowest PRB index (and aDMRS CS value related to UL data transmission) with respect to a UL datatransmission resource region in UL SF-1 on the basis of I_(PHICH)=0. APHICH resource index corresponding to UL SF-2 may be assigned a PHICHresource index linked to the lowest PRB index (and a DMRS CS valuerelated to UL data transmission) with respect to a UL data transmissionresource region in UL SF-2 on the basis of I_(PHICH)=0. When the SCC isset to a mode in which transmission of a maximum of two TBs is supportedin one UL SF, the PHICH resource index corresponding to the first TB ofUL SF-1 (or UL SF-2) may be determined as a PHICH resource indexI_(PHICH)=0 linked to the lowest PRB index k_(PRB) (and a DMRS CS valuerelated to UL data transmission) used for UL data transmission in ULSF-1 (or UL SF-2) on the basis of I_(PHICH)=0 and the PHICH resourceindex corresponding to the second TB of UL SF-1 (or UL SF-2) may bedetermined as a PHICH resource index n_(PHICH,1) linked to k_(PRB)+1(and the DMRS CS value related to UL data transmission) on the basis ofI_(PHICH)=0.

The aforementioned method may limit a case in which the lowest PRB index(k_(PRB) and/or k_(PRB)±1 when SCC UL supports transmission of a maximumof two TBs) allocated to UL data transmitted through UL SF-1 and UL SF-2and the DMRS CS value related thereto are identically assigned in ULSF-1 and UL SF-2 in order to avoid collision between PHICH resourcescorresponding to UL SF-1 and UL SF-2.

The method proposed by the present invention may equivalent tooperations of determining I_(PHICH) as defined for UD-Cfg #0, which isRef-Cfg of UG/PHICH timing (i.e. I_(PHICH)=1 for UL data transmission ofSFs #4 and #9 and I_(PHICH)=0 for UL data transmission of other SFs),and obtaining PHICH resource indices based on the following equations.

n _(PHICH) ^(group)=(I _(PRB) _(—) _(RA) +n _(DMRS))mod N _(PHICH)^(group)

n _(PHICH) ^(seq)=(└I _(PRB) _(—) _(RA) /N _(PHICH) ^(group) ┘+n_(DMRS))mod 2N _(SF) ^(PHICH)  [Equation 3]

In addition, the method proposed by the present invention may beequivalent to operations of determining I_(PHICH) according to UD-Cfg#0, which is Ref-Cfg of UG/PHICH timing (i.e. I_(PHICH)=1 for UL datatransmission of SFs #4 and #9 and I_(PHICH)=0 for UL data transmissionof other SFs), and obtaining PHICH resource indices (i.e. PHICH groupindices) based on one of the following equations.

n _(PHICH) ^(group)=(I _(PRB) _(—) _(RA) +n _(DMRS))mod N _(PHICH)^(group) +I _(PHICH) N _(PHICH) ^(group)+offset

n _(PHICH) ^(group)=(I _(PRB) _(—) _(RA) +n _(DMRS))mod N _(PHICH)^(group)+(I _(PHICH)+offset)N _(PHICH) ^(group)  [Equation 4]

In the first equation, the offset may be set to N (in the case of SFs #4and #9) or 0 (in the case of other SFs). In the second equation, theoffset may be set to −1 (in the case of SFs #4 and #9) or 0 (in the caseof other SFs).

Alt 1) Setting of Offset for PHICH Resource Index (or DMRS CS)

A PHICH resource index corresponding to UL data of UL SF-1 may bedetermined as a PHICH resource index (e.g. n_(PHICH)) linked to thelowest PRB index (and the DMFS CS value) with respect to the UL datatransmission region. A PHICH resource index corresponding to UL data ofUL SF-2 may be determined as a PHICH resource index corresponding ton_(PHICH)+offset. Equivalently, a PHICH resource index corresponding toUL data of UL SF-2 may be determined as a PHICH resource index inferredfrom a DMRS CS value obtained by adding an offset to a value signaledthrough a DMRS CS field in a UG PDCCH (or a PHICH resource indexinferred from a value obtained by adding an offset to a parameter usedfor PHICH resource index determination). Here, the offset may bepre-fixed or cell-/UE-specifically set through L1 (Layer 1)/L2 (Layer2)/RRC (radio resource control)/broadcast signaling. Alternatively, theoffset may not be applied when the PHICH resource index corresponding toUL SF-2 is determined, whereas the offset may be applied when the PHICHresource index corresponding to UL SF-1 is determined. The offset ispreferably set to a non-zero value in consideration of PHICH resourcecollision.

When SCC UL is set to a mode supporting transmission of a maximum of twoTBs, PHICH resources corresponding to the two TBs transmitted through ULSF-1 (or UL SF-2) may be determined as PHICH resources corresponding toPHICH resource indices n_(PHICH,0) and n_(PHICH,1) respectively linkedto the lowest PRB index k_(PRB) and k_(PRB)+1. PHICH resourcescorresponding to the two TBs transmitted through UL SF-2 (or UL SF-1)may be determined as PHICH resources corresponding to two PHICH resourceindices inferred from a value obtained by adding an offset to k_(PRB),k_(PRB)+1, DMRS CS or a parameter related to PHICH resourcedetermination. Here, the offset may be set to a value that does notcorrespond to {−1, 0, 1} in consideration of PHICH resource collision.

Alt 2) Application of Operation of Permitting Only UL Grant BasedRetransmission without Referring to PHICH

In the case of UL data of UL SF-1, PHICH based non-adaptiveretransmission (and UL grant reception based adaptive retransmission)may be permitted. Here, a PHICH resource corresponding to UL SF-1 may bedetermined as a PHICH resource corresponding to a PHICH resource indexlinked to the lowest PRB index (and the DMRS CS value) with respect tothe UL data transmission resource region. When SCC UL is set to a modesupporting transmission of up to two TBs, PHICH resources correspondingto two TBs transmitted through UL SF-1 may be determined as PHICHresources corresponding to a PHICH resource index n_(PHICH,0) linked tothe lowest PRB index k_(PRB) and a PHICH resource index n_(PHICH,1)linked to k_(PRB)+1.

In the case of UL data of UL SF-2, a PHICH resource corresponding to theUL data may not be allocated thereto and only UL grant based adaptiveretransmission may be permitted without referring to a PHICH (referredto as PHICH-less operation). To permit only UL grant basedretransmission, a UE may transmit ACK to a HARQ entity (specifically, aHARQ process) of MAC layer in a DL SF in which a PHICH with respect toUL SF-2 needs to be received. UL data retransmission may be performedwhen NACK or DTX is detected because the MAC layer may determine thatDTX is generated in UL data/PHICH when the UE reports no HARQ responseto the MAC layer in the DL SF where the PHICH with respect to UL SF-2needs to be received. When a UL grant is received in a DL SF throughwhich the PHICH with respect to UL SF-2 needs to be received, the UE mayperform retransmission/initial transmission of UL data according to anew data indicator (NDI) in the UL grant.

Conversely, the PHICH based scheme may be applied to UL SF-2 and thePHICH-less operation may be applied to UL SF-1. That is, in the case ofUL SF-1, only UL grant based adaptive retransmission may be permittedwithout corresponding PHICH resource allocation and without referencethereto.

FIG. 19 illustrates a generalized example of the HARQ process accordingto Alt 2. While the figure shows UE operation for convenience, it isapparent that an eNB can perform a corresponding operation.

Referring to FIG. 19, the UE aggregates a plurality of CCs (S1902).Here, the CCs may have different subframe configurations (e.g. CCshaving different TDD UL-DL configurations are aggregated or a TDD CC andan FDD CC are aggregated). For example, a scheduling CC and a scheduledCC may be aggregated and the scheduled CC may have UL-DL configuration#0. Then, the UE may receive scheduling information (UL grant PDCCH) ona UL SF of the scheduled CC through the scheduling CC (S1904). When thescheduled CC has UL-DL configuration #0, the UL grant PDCCH may includescheduling information on UL SF-1 and/or UL SF-2. UL SF-1 precedes ULSF-2. Resource allocation with respect to UL SF-1 and/or UL SF-2 may beindicated using a UL index in the UL grant PDCCH. Then, the UE maytransmit UL data through the UL SF of the scheduled CC according to thescheduling information (S1906). According to the method proposed by thepresent invention, when a PHICH resource corresponding to the UL SF ispresent in a DL SF of the scheduling CC, which corresponds to the UL SF(e.g. in the case of UL SF-1), PHICH-based retransmission and/or ULgrant-based retransmission are permitted for data of the UL SF. On thecontrary, when the PHICH resource corresponding to the UL SF is notpresent in the DL SF of the scheduling CC, which corresponds to the ULSF (e.g. in the case of UL SF-2), only UL grant-based retransmission maybe permitted for the data of the UL SF.

Alt 2-1) Application of Operation of Permitting Only UL Grant BasedRetransmission without Reference to PHICH

PHICH resources corresponding to UL data of UL SF-1 and UL data of ULSF-2 may not allocated thereto and only UL grant based adaptiveretransmission may be permitted without referring to a PHICH. That is,the PHICH-less operation is applicable to both UL SF-1 and UL SF-2.

Alt 3) Transmission of ACK/NACK Bundled Per UL SF/Between UL SFs Througha Single PHICH Resource

Bundling (e.g. logical AND operation) may be performed on A/N for ULdata of UL SF-1 and A/N for UL data of UL SF-2 and then the bundled A/Nsmay be transmitted through a single PHICH resource. The PHICH resourcemay be determined as a PHICH resource corresponding to a PHICH resourceindex linked to the lowest PRB index (and the DMRS CS value) withrespect to the UL data transmission resource region of UL SF-1 (or ULSF-2).

When the SCC UL is set to a mode supporting transmission of up to twoTBs, it is possible to use PHICH resource index n_(PHICH,0) linked tothe lowest PRB index k_(PRB) of the UL data transmission resource regionof a specific UL SF (UL SF-1 or UL SF-2) and PHICH resource indexn_(PHICH,1) linked to k_(PRB)+1. In addition, it is possible to usePHICH resource index n_(PHICH,U1) linked to the lowest PRB indexk_(PRB,U1) of the UL data transmission resource region of UL SF-1 andPHICH resource index n_(PHICH,U2) linked to the lowest PRB indexk_(PRB,U2) of the UL data transmission resource region of UL SF-2. Onthe basis of this, it is possible to consider a method of i)transmitting/receiving bundled ACK/NACK for UL SF-1 TBs throughn_(PHICH,0) (or n_(PHICH,U1)) or transmitting/receiving ACK/NACK for ULSF-2 TBs through n_(PHICH,1) (or n_(PHICH,U2)) or ii)transmitting/receiving bundled ACK/NACK for the first TB transmittedthrough the two UL SFs by means of n_(PHICH,0) (or n_(PHICH,U1)) andtransmitting/receiving bundled ACK/NACK for the second TB throughn_(PHICH,1) (or n_(PHICH,U2)).

When a DL SF of the MCC, which corresponds to common PHICH timing fortwo specific UL SFs (specifically, two pieces of UL data transmittedthrough the UL SFs) on the SCC, does not belong to UG/PHICH timing (e.g.DL SF in which a PHICH resource is reserved) set to the MCC (i.e. whenPHICH resource allocation and transmission for the two pieces of UL dataare simultaneously required while there is no reserved PHICH resource),Alt 2-1 is applicable.

When the MCC corresponds to UL-Cfg #0 and the SCC is set to UD-Cfg otherthan UD-Cfg #0 in a cross-CC scheduling case, a method other thansolution 1 or 2 is applicable. For example, Ref-Cfg of UG/PHICH timingfor the SCC UL data may be determined as UD Cfg (which may includeUD-Cfg of the SCC) (e.g. UD Cfg #1 or UD-Cfg #6) other than UD-Cfg #0(corresponding to the UL union of the MCC and SCC or UD-Cfg of the MCC).That is, the aforementioned case may refer to a case in which UD-Cfg ofthe MCC is UD-Cfg #0 and Ref-Cfg of UG/PHICH timing for the SCC is notset to UD-Cfg #0. Here, 2×PHICH resource may be reserved in all or someDL SFs since the MCC corresponds to UD-Cfg #0. In this case, a PHICHwith respect to a single SCC UL SF (UL data transmitted through thesame) may be transmitted through a single MCC DL SF according toRef-Cfg.

To achieve this, Alt 0 may be applied (i.e. PHICH resource indices aredetermined by applying I_(PHICH)=0 for all UL SFs (UL data transmittedthrough the same) of the SCC), I_(PHICH)=0 and I_(PHICH)=1 may berespectively applied to a case in which 1×PHICH resource is reserved anda case in which 2×PHICH resource is reserved, or I_(PHICH)=0 may beapplied to the case in which 1×PHICH resource is reserved and it may bedetermined which one of I_(PHICH)=0 and I_(PHICH)=1 is applied to thecase in which 2×PHICH resource is reserved. I_(PHICH) may besemi-statically set through RRF signaling, for example, explicitlyindicated by adding a (1-bit) field in the UL grant PDCCH, or implicitlylinked to a specific field value in the UL grant PDCCH (e.g. I_(PHICH)depends on RB allocation information and/or DMRS CS value).

Which one of the aforementioned methods (Alt 0 to Alt 3) is applied maybe cell-specifically or UE-specifically set through RRC signaling.

When Alt 0 (applying I_(PHICH)=0) is employed, I_(PHICH) (correspondingto UL data transmission in the SCC) may be determined according toUD-Cfg (i.e. MCC UD-Cfg) of the MCC and/or Ref-Cfg (i.e. SCC Ref-Cfg) ofUG/PHICH timing for the SCC (limited to TDD CA of different UD-Cfgs).

Alt 0-1) Setting of I_(PHICH) According to Whether MCC UD-Cfg or SCCRef-Cfg Corresponds to UD-Cfg #0

When MCC UD-Cfg corresponds to UD-Cfg #0, I_(PHICH) may be set to 0 or 1according to SF. When MCC UD-Cfg is not UD-Cfg #0, I_(PHICH) may be setto 0 for all SFs. In addition, I_(PHICH) may be set to 0 or 1 accordingto SF when SCC Ref-Cfg is UD-Cfg #0 and set to 0 for all SFs when SCCRef-Cfg is UD-Cfg #0.

Alt 0-2) Setting of I_(PHICH) According to Whether Both MCC UD-Cfg andSCC Ref-Cfg Correspond to UD-Cfg #0

I_(PHICH) may be set to 0 or 1 according to SF when both MCC UD-Cfg andSCC Ref-Cfg correspond to UD-Cfg #0 and set to 0 for all SFs (i.e. ULdata transmission in all (UL) SFs) when at least one of MCC UD-Cfg andSCC Ref-Cfg does not correspond to UD-Cfg #0. Specifically, when bothMCC UD-Cfg and SCC Ref-Cfg correspond to UD-Cfg #0, I_(PHICH) may be setto 1 for UL data transmission in SFs #4 and #9 and set to 0 for UL datatransmission in the remaining SFs.

When MCC UD-Cfg corresponds to UD-Cfg #0 whereas SCC Ref-Cfg does notcorrespond to UD-Cfg #0, 1) I_(PHICH) may be set to 0 or 1 according to(UL data transmission) SF for the MCC and I_(PHICH) may be set to 0 forall SFs with respect to the SCC or 2) I_(PHICH) corresponding to all SFsmay be set to 0 for both the MCC and SCC. When MCC UD-Cfg does notcorrespond to UD-Cfg #0, I_(PHICH) corresponding to all (UL datatransmission) SFs may be set to 0 for both the MCC and SCC (irrespectiveof SCC Ref-Cfg).

Alt 0-3) Setting of I_(PHICH) Irrespective of Combination of MCC and SCC

I_(PHICH) may be set to 0 for all SFs (i.e. UL data transmission in all(UL) SFs) all the time irrespective of a combination of the MCC and SCC(i.e. irrespective of whether MCC UD-Cfg and/or SCC Ref-Cfg correspondto UD-Cfg #0).

Specifically, when MCC UD-Cfg corresponds to UD-Cfg #0, 1) I_(PHICH) maybe set to 0 or 1 according to (UL data transmission) SF for the MCC andI_(PHICH) may be set to 0 for all SFs with respect to the SCC or 2)I_(PHICH) corresponding to all SFs may be set to 0 for both the MCC andSCC (irrespective of SCC Ref-Cfg). When MCC UD-Cfg does not correspondto UD-Cfg #0, I_(PHICH) corresponding to all (UL data transmission) SFsmay be set to 0 for both the MCC and SCC (irrespective of SCC Ref-Cfg).

In addition, in the case of PCC (limited to TDD CA for differentUD-Cfgs), 1) I_(PHICH) may be set to 0 or 1 according to (UL datatransmission) when PCC UD-Cfg corresponds to UD-Cfg #0, and I_(PHICH)may be set to 0 for all SFs or 2) I_(PHICH) may be set to 0 for all SFsirrespective of PCC UD-Cfg when PCC UD-Cfg corresponds to UD-Cfg.

When Ref-Cfg of UG/PHICH timing for a specific CC is set to UD-Cfg (e.g.UD-Cfg #N (N>0)) other than UD-Cfg (e.g. UD-Cfg #0 or UD-Cfg #N (N>0))of the specific CC or to UD-Cfg #0 (and/or when the MCC corresponds tothe SCC (i.e. cross-CC scheduling is not set or non-cross-CC schedulingis set for the specific CC), all the above-described proposed methodsmay be equally/similarly applied to determine/transmit a PHICH resourcecorresponding to UL data transmitted through the specific CC.

In the specification, setting of I_(PHICH) to 0 or 1 may meandetermining whether to add N_(PHICH) ^(group) in PHICH resource indexdetermination (while I_(PHICH) is set according to Ref-Cfg). That is,setting of I_(PHICH) to 0 or 1 may mean determining which one of thefollowing equations will be applied.

n _(PHICH) ^(group)=(I _(PRB) _(—) _(RA) +n _(DMRS))mod N _(PHICH)^(group)

n _(PHICH) ^(group)=(I _(PRB) _(—) _(RA) +n _(DMRS))mod N _(PHICH)^(group) +N _(PHICH) ^(group)  [Equation 5]

FIG. 20 illustrates a BS and a UE of a wireless communication system,which are applicable to embodiments of the present invention. When thewireless communication system includes a relay, the BS or UE can bereplaced by the relay.

Referring to FIG. 20, the wireless communication system includes a BS110 and a UE 120. The BS 110 includes a processor 112, a memory 114 anda radio frequency (RF) unit 116. The processor 112 may be configured toimplement the procedures and/or methods proposed by the presentinvention. The memory 114 is connected to the processor 112 and storesinformation related to operations of the processor 112. The RF unit 116is connected to the processor 112 and transmits and/or receives an RFsignal. The UE 120 includes a processor 122, a memory 124 and an RF unit126. The processor 122 may be configured to implement the proceduresand/or methods proposed by the present invention. The memory 124 isconnected to the processor 122 and stores information related tooperations of the processor 122. The RF unit 126 is connected to theprocessor 122 and transmits and/or receives an RF signal. The BS 110and/or the UE 120 may include a single antenna or multiple antennas.

The embodiments of the present invention described hereinbelow arecombinations of elements and features of the present invention. Theelements or features may be considered selective unless otherwisementioned. Each element or feature may be practiced without beingcombined with other elements or features. Further, an embodiment of thepresent invention may be constructed by combining parts of the elementsand/or features. Operation orders described in embodiments of thepresent invention may be rearranged. Some constructions of any oneembodiment may be included in another embodiment and may be replacedwith corresponding constructions of another embodiment. It will beobvious to those skilled in the art that claims that are not explicitlycited in each other in the appended claims may be presented incombination as an embodiment of the present invention or included as anew claim by a subsequent amendment after the application is filed.

In the embodiments of the present invention, a description is madecentering on a data transmission and reception relationship among a BS,a relay, and an MS. In some cases, a specific operation described asperformed by the BS may be performed by an upper node of the BS. Namely,it is apparent that, in a network comprised of a plurality of networknodes including a BS, various operations performed for communicationwith an MS may be performed by the BS, or network nodes other than theBS. The term ‘BS’ may be replaced with the term ‘fixed station’, ‘NodeB’, ‘enhanced Node B (eNode B or eNB)’, ‘access point’, etc. The term‘UE’ may be replaced with the term ‘Mobile Station (MS)’, ‘MobileSubscriber Station (MSS)’, ‘mobile terminal’, etc.

The embodiments of the present invention may be achieved by variousmeans, for example, hardware, firmware, software, or a combinationthereof. In a hardware configuration, the methods according to theembodiments of the present invention may be achieved by one or moreApplication Specific Integrated Circuits (ASICs), Digital SignalProcessors (DSPs), Digital Signal Processing Devices (DSPDs),Programmable Logic Devices (PLDs), Field Programmable Gate Arrays(FPGAs), processors, controllers, microcontrollers, microprocessors,etc.

In a firmware or software configuration, the embodiments of the presentinvention may be implemented in the form of a module, a procedure, afunction, etc. For example, software code may be stored in a memory unitand executed by a processor. The memory unit is located at the interioror exterior of the processor and may transmit and receive data to andfrom the processor via various known means.

Those skilled in the art will appreciate that the present invention maybe carried out in other specific ways than those set forth hereinwithout departing from the spirit and essential characteristics of thepresent invention. The above embodiments are therefore to be construedin all aspects as illustrative and not restrictive. The scope of theinvention should be determined by the appended claims and their legalequivalents, not by the above description, and all changes coming withinthe meaning and equivalency range of the appended claims are intended tobe embraced therein.

INDUSTRIAL APPLICABILITY

The present invention is applicable to a UE, BS or other apparatuses(e.g. a relay) of a wireless communication apparatus. Specifically, thepresent invention is applicable to a method for transmitting controlinformation and an apparatus for the same.

1. A method for performing a data retransmission by a user equipment(UE) in a wireless communication system, the method comprising:configuring, by the UE, a first cell and a second cell having differentsubframe patterns, wherein every downlink (DL) subframe of the firstcell has only a basic set of hybrid automatic repeat requestacknowledgement (HARQ-ACK) resources, and the second cell includes afirst uplink (UL) subframe associated with the basic set of HARQ-ACKresources and a second UL subframe associated with an additional set ofHARQ-ACK resources; transmitting, by the UE, data via the second cellbased on a UL grant of the first cell; and retransmitting, by the UE,the data according to control information of the first cell, wherein thedata is retransmitted using at least a non-adaptive retransmissionprocedure when the data is transmitted in the first subframe of thesecond cell, and wherein the data is retransmitted using only anadaptive retransmission procedure when the data is transmitted in thesecond subframe of the second cell.
 2. The method of claim 1, whereinthe data is retransmitted using at least one of the non-adaptiveretransmission procedure or adaptive retransmission procedure the whenthe data is transmitted in the first subframe of the second cell.
 3. Themethod of claim 1, wherein the non-adaptive retransmission procedure isperformed based on a physical hybrid ARQ indicator channel (PHICH), andthe adaptive retransmission procedure is performed based on an UL grant.4. The method of claim 1, wherein the data is retransmitted based on atleast one of a PHICH and an UL grant when the data is transmitted in thefirst subframe of the second cell, and wherein the data is retransmittedonly based on an UL grant when the data is transmitted in the secondsubframe of the second cell.
 5. The method of claim 1, wherein thesecond cell has a subframe pattern of Time Division Duplex (TDD) UL-DLconfiguration #0 as shown below: UL-DL Subframe number configuration 0 12 3 4 5 6 7 8 9 0 D S U U U D S U U U 1 D S U U D D S U U D 2 D S U D DD S U D D 3 D S U U U D D D D D 4 D S U U D D D D D D 5 D S U D D D D DD D 6 D S U U U D S U U D

wherein D indicates a DL subframe, U indicates a UL subframe, and Sindicates a special subframe.
 6. The method of claim 5, wherein thefirst cell has a subframe pattern of any one of TDD UL-DL configuration#1 to #6.
 7. The method of claim 1, wherein the UL grant includes ULscheduling information for the first UL subframe or the second ULsubframe, the first UL subframe preceding the second UL subframe.
 8. Themethod of claim 1, wherein the first cell is a scheduling cell and thesecond cell is a scheduled cell.
 9. The method of claim 1, wherein thedata is transmitted through a physical uplink shared channel (PUSCH).10. A user equipment (UE) configured to perform a hybrid automaticrepeat request (HARQ) process in a wireless communication system, the UEcomprising: a radio frequency (RF) unit; and a processor operativelyconnected to the RF unit and configured to: configure a first cell and asecond cell having different subframe patterns, wherein every downlink(DL) subframe of the first cell has only a basic set of hybrid automaticrepeat request acknowledgement (HARQ-ACK) resources, and the second cellincludes a first uplink (UL) subframe associated with the basic set ofHARQ-ACK resources and a second UL subframe associated with anadditional set of HARQ-ACK resources, transmit data via the second cellbased on a UL grant of the first cell, and retransmit the data accordingto control information of the first cell, wherein the data isretransmitted using at least a non-adaptive retransmission procedurewhen the data is transmitted in the first subframe of the second cell,and wherein the data is retransmitted using only an adaptiveretransmission procedure when the data is transmitted in the secondsubframe of the second cell.
 11. The UE of claim 10, wherein the data isretransmitted using at least one of the non-adaptive retransmissionprocedure or adaptive retransmission procedure the when the data istransmitted in the first subframe of the second cell.
 12. The UE ofclaim 10, wherein the non-adaptive retransmission procedure is performedbased on a physical hybrid ARQ indicator channel (PHICH), and theadaptive retransmission procedure is performed based on an UL grant. 13.The UE of claim 10, wherein the data is retransmitted based on at leastone of a PHICH and an UL grant when the data is transmitted in the firstsubframe of the second cell, and wherein the data is retransmitted onlybased on an UL grant when the data is transmitted in the second subframeof the second cell.
 14. The UE of claim 10, wherein the second cell hasa subframe pattern of Time Division Duplex (TDD) UL-DL configuration #0as shown below: UL-DL Subframe number configuration 0 1 2 3 4 5 6 7 8 90 D S U U U D S U U U 1 D S U U D D S U U D 2 D S U D D D S U D D 3 D SU U U D D D D D 4 D S U U D D D D D D 5 D S U D D D D D D D 6 D S U U UD S U U D

wherein D indicates a DL subframe, U indicates a UL subframe, and Sindicates a special subframe.
 15. The UE of claim 14, wherein the firstcell has a subframe pattern of any one of TDD UL-DL configuration #1 to#6.
 16. The UE of claim 10, wherein the UL grant includes UL schedulinginformation for at least one of the first UL subframe or the second ULsubframe, the first UL subframe preceding the second UL subframe. 17.The UE of claim 10, wherein the first cell is a scheduling cell and thesecond cell is a scheduled cell.
 18. The UE of claim 10, wherein thedata is transmitted through a physical uplink shared channel (PUSCH).